Question #c646d

1 Answer
Jun 5, 2017

Answer:

You convert the mass to moles and then multiply by Avogadro's number.

Explanation:

Step 1. Convert the mass to moles

One mole of #"NO"# has a mass of (14.01 + 16.00) g = 30.01 g

#"Moles of NO" =75 color(red)(cancel(color(black)("g NO"))) × "1 mol NO"/(30.01 color(red)(cancel(color(black)("g NO")))) = "2.50 mol NO"#

Step 2. Convert moles to molecules

One mole of a compound contains Avogadro's number (#6.022 × 10^23#) of molecules.

#"Molecules of NO" = 2.50 color(red)(cancel(color(black)("mol NO"))) × (6.022 × 10^23color(white)(l) "molecules NO")/(1 color(red)(cancel(color(black)("mol NO"))))#

#= 1.5 × 10^24 color(white)(l)"molecules NO"#

Your sample contains #1.5 × 10^24 color(white)(l)"molecules of NO"#.